Commercially deployed rotor sail gets class nod after real-world use

The TADC was retrospectively presented to Anemoi during a special ceremony at SMM in Hamburg, Germany, on 5 September 2024  and validates the company’s 35-m rotor sail design complies with DNV’s technical standard (ST-0511) for Wind Assisted Propulsion Systems (WAPS).

Rotor sails are updated versions of Flettner rotors, vertical cylinders that, when driven to rotate, harness the renewable power of the wind to propel ships. These highly efficient mechanical sails capitalise on the aerodynamic phenomenon known as the Magnus Effect to provide additional thrust to vessels. 

Anemoi chief executive Kim Diederichsen said, "We are delighted to have received this important type-approval from DNV, which is a testament to the rigorous design and engineering work undertaken by our team. This certification provides shipowners and operators with the assurance they need to invest in our 5 x 35m rotor sail solution, which has already been selected for upcoming installations on several vessels.”

DNV senior principal engineer Hasso Hoffmeister added, “Over the last few years, WAPS technologies have continued to go from strength to strength, with the number of installations tripling in just the last year according to estimates from the IWSA.” 

“This growth has been built on innovation, safety and trusted expertise. We are very pleased to build on the excellent collaboration with Anemoi with the presentation of this certificate. Together, we are continuing to develop the technical standards and class notations that will enable the momentum behind WAPS to continue to build and enhance shipping’s drive to greater sustainability.”

In May, an Anemoi rotor sail was installed on DNV-classed bulker Berge Neblina, representing the first commercial deployment of this product size. Anemoi has also previously obtained a full Statement of Design appraisal for the rotor sail, and has additional installations planned later this year and into 2025, including on Sohar Max, a 400,000-dwt VLOC operated by mining giant Vale.